Archive for the '07 Avalanche Avoidance' Category

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Skiing During Wartime

Published on January 7, 2009 in 07 Avalanche Avoidance. 3 Comments Tags: .

The Wasatch Mountains have been getting some good storms lately and it has been dumping snow here all day.  Yippy!  I’ve had to plow out the driveway twice in eight hours, the wind is howling and the avalanche danger is on the rise.  All of which means it is a good time to go skiing this morning. *

Gusting to 34mph with lots of snow. Three feet to the viewers right and this person would be going down in a slide for sure.

Skiing during high avalanche danger is a double edged sword – on one hand there is no better way to experience unstable snow than to stomp around on it, yet at the same time stomping in the wrong area can be lethal.  Here are some thoughts on skiing during periods of high danger:

  • It is more about the experience than the turns.  Pick an ultrasafe area, scale back on your ambitions and think of it as more of a field trip than a skiing tour.
  • Look for low angle terrain and safe ridge-lines.  Especially avoid big hanging fields above you that might naturally release and sweep down on top of you.
  • A like-minded partner is essential to avoid getting peer pressured into steeper terrain.
  • Part of the challenge of going out on deep & dangerous days is to find slopes that are steep enough to ski down, but not steep enough to avalanche.  This may be impossible at times, so be prepared to get shut down and follow your skin track back.
  • Be aware of routes that are 95% safe.  If it is a four mile tour with one little 200′ exposed section, you can bet that during high danger that’s where the accidents will happen. 
  • Practice impeccable safe travel techniques.
There’s a time & place for Meadow Skipping, like during high danger storm days.

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* It was not at all as expected!  I was geared up for a howling blizzard, and it turned out to be a full-on Pineapple Express – warm, balmy, hardly any wind and some really slooooow inverted snow.  The avalanche danger wasn’t anywhere near as touchy as I thought it would be, but then again, we weren’t pushing it too hard either.

The Extended Column Test (ECT)

Published on January 6, 2009 in 07 Avalanche Avoidance. 13 Comments Tags: .

As much as anything, I love learning new snow stability test as I get bored doing the same old ones over and over.  I use to do a lot of Reusch Block tests, but over the years they started getting smaller and smaller.  Nowadays, I’m into digging a pit which is big enough to preform three isolated column tests – one shovel shear, one compression, and then a repeat of whichever of those two seemed most valuable.  I prefer lots of half-assed pits over one mega pit as conditions vary so much.  Because of this, I dig a lot of my pits with my skis on and only spend about 5-10 minutes max per pit.

I was out with Dylan Freed the other day who showed me the Extended Column Test, which I like as it uses the same pit format as the above tests and shows not only weak layers, but also gives you an idea of how easily they will propagate. The test is just like a compression test, except you use an extended, triple-wide column, and thus the name – the Extended Column Test.

Dylan also passed along the written description from the  Applied Snow and Avalanche Research at the University of Calgary which can be found here.

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Developing an Eye for Angles – Part 2

Published on January 2, 2009 in 07 Avalanche Avoidance. 6 Comments Tags: .

Part of the challenge of correctly identifying slope angles by eye is that they often look much steeper when viewed straight-on than they do from the side.  (This is also a good photography trick – shooting straight-on, like from a helicopter or across a valley makes the slopes look lots steeper).  A classic case of this is Mt. Superior, which when viewed directly across the canyon from Alta or Snowbird, looks really steep, but when you actually ski it, it’s about like a black diamond run at a resort – not too bad. 

The steep looking Monte Cristo Headwall as seen head-on from Mt. Superior. Photo by Carl Skoog
The same 30-degree headwall as seen from the side. Alex Lowe digging a pit.

Something to keep in mind is that your angle-sense changes when you move to different areas.  For instance, the snow in Alaska sticks to steeper slopes than in the Wasatch, so all of those little visual clues you subconsciously pick up on are off.  As a result, I often underestimate my maritime snowpack angles and overestimate the continental ones.

Any way you physically measure a slope is better than nothing, although the generally agreed on best method is to sight down it with an accurate clinometer, or get it from a distant side view.  Measuring it directly on the snow, or on a pole on the snow (as shown in yesterday’s post) may pick up unwanted dips or roll-overs.  Keeping a compass/clinometer in a chest pouch or front zipper pocket makes it easy and painless to grab a quick angle.

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Developing an Eye for Angles – Part 1

Published on January 1, 2009 in 07 Avalanche Avoidance. 0 Comments Tags: .

An experienced car mechanic can look at a nut or bolt from ten feet away and instantly tell you what size it is down to the 64th of an inch.  It is not magic, but more a case of repetitive familiarity within a certain range.  Cars tend to use bolts in the 1/4″ to 1″ range, so after a few hundred times of fitting sockets to them, you start to develop a eye for what size they are.

The same idea applies for slope angles, which in terms of avalanche danger, is a key factor.  Although my eyes/brain are not accurately calibrated for the sub 25-degree range, or over 50-degrees, I can usually pick out a slope angle in the 30-45 degree range to within a degree or so at a glance.  Like a mechanic, this is more the result of first making a guesstimate, then trying it (with a clinometer in the case of a slope).  After doing this a few hundred times you start to get pretty accurate at it.  If I’m with a group, I make everyone guess (including myself) before taking the actual measurement, just for the fun of it.

Checking the slope angle in the Tetons. Photo by Doug Coombs.

The significance of developing an eye for angles is that often, just a few degrees can make a huge difference.  For instance, say you are skinning up a 30 degree ridgeline, which then contours around into a slightly steeper bowl.  In this case, you will be changing aspects (north/south/east/west) AND bumping the angle up towards the prime 38-degree avalanche strike zone.  It is subtle, but within a few feet you can go from relative safety to dangerous.

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Deciphering the Avalanche Rose

Published on December 23, 2008 in 07 Avalanche Avoidance. 9 Comments Tags: .

The idea of an “avalanche rose” has been around for a while, but has been making its way into avalanche forecasts where it is one of my favorite quick-hit summaries of the current avalanche stability.  The “rose” part come from the concept of a compass rose (north, south, east & west pointers with sub quads) and the avalanche part comes from, well, avalanches.  I like the avalanche rose as it is a very quick, graphical overview.  I wouldn’t ski a slope based only on the info gleaned from an avalanche rose diagram, but it would give me a big head-start on where to start looking for trouble or safe skiing for the day.

As the skier sees Little Cottonwood Canyon…
… the same view through the eyes of the avalanche rose. In the above illustration, the skier probably would have triggered an avalanche up in the red zone.

The avalanche rose is a stylized top view of a mountain which splits the world into aspects and elevations, then assigns an avalanche danger accordingly.  It is a rough estimate and not like you can suddenly cross the 10,000′ foot line, or from NW to North and have the danger dissipate, but it gives a good general idea.  Much like a traffic light, red means “stop - high danger”  (beyond that is extreme/black, which is rare), and green is “go – low danger,” which makes it easy to figure out. 

The avalanche rose in action on a daily UAC forecast:

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Charting Automated Weather Station Data

Published on November 26, 2008 in 07 Avalanche Avoidance. 6 Comments Tags: .

When it comes to forecasting avalanche conditions, an important element is looking at the data and trends of the last 24 hours.  For this, automated snow stations, as discussed yesterday, are great, but they present you with an snoot-full of data that can be hard to decipher. Instead, what I like to do is have Excel import the data, then chart it for me so that with just a quick glance, I can see if it got above freezing during the day, if the winds were howling while I slept or how much new snow came down.

Charted automated weather station temperature data. At a glance, this looks like good corn snow conditions with cold nights and warm days. Too bad there is no snow to corn up.

Ninety percent of charting this data has to do with being familiar with Excel, of which I know just enough of to figure out the basics.  I learned how to do this while working at the Utah Avalanche Forecast Center where I had set up an elaborate version.  The downfall of this is that the weather stations often go down, or some weather tech guy/girl changes the data format, so they fancy systems never worked for very long.  I’ve since simplified my strategy and only use a few select chunks of data from the most reliable stations, then use the charts as starting points for looking at the snow pack whenever I go out.  Once you get the charts set up, it is only a matter of hitting the “refresh” button to get them to instantly update with new data.

24 hour wind graph. If there was any new snow associated with this period, avalanche danger would most definitely be going up. Charts like this are useful as you may show up at the trailhead with no apparent wind (right hand side of the graph), yet it has obviously been windy for the last 24-hour period.

How to Chart Automated Weather Station data Geekfest:

Importing Weather Data
Open a blank Excel spreadsheet document
Place your cursor in the top, left hand box (A1)
In the top toolbar, select “Data”
Under “Data” select “Import External Data”
The “Select Data Source” window will open
In the “File name:” box, insert the entire html address of your weather station of choice
Click “Open”

Excel will connect (hopefully) to the weather station and display a group of little arrow icons on the fields which are extractable
Click on the table which holds the actual weather data (time, wind, etc…)
Excel grabs the data and inserts it into your spreadsheet

Charting
Save your data on “Sheet 1”
Go to the blank “Sheet 2”
Select “Insert” on the main toolbar, then “Chart”
Click where you want the chart to be
Select what kind of chart you want (I like the basic “line” chart)
On the next window, where it says “Data Range” click the little range box to the right, then go to Sheet 1 and drag your cursor down the data column you want to chart (wind, temp, etc.)
From here, click through a bunch of color, line and title boxes, then, voila! you have a chart of the last 24 hours.

Updating
Save your spreadsheet with a suitable name.
Now, once you open this spreadsheet again, you can hit the “Refresh Data” button on the External Data toolbar and Excel will go to the website, grab the latest info and insert it and the charts will update. Neat-oh!

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Inside Info – Part II

Published on July 31, 2008 in 07 Avalanche Avoidance. 0 Comments Tags: , .

The snowpack is the third major factor and also the trickiest one.  Like the weather, its history is more important than its immediate surface conditions. The plot thickens with the snowpack as there are almost always weaknesses in it, but they are difficult to quantify.  Snow is the building block of avalanches, but it is these tiny weaknesses between the blocks that actually cause them. Assessing the snowpack is difficult because these paper-thin layers are hard to identify and quantify amidst many feet of snow.

An avalanche triggered by a very surprised mountain lion in the Wasatch Mountains. No cats were hurt during the making of this photo and the tracks led away from the debris.
An avalanche triggered by a very surprised mountain lion in the Wasatch Mountains. No cats were hurt during the making of this photo and the tracks led away from the debris.

Thinking of avalanches in terms of terrain, weather and snowpack simplifies the decision process as you need all or a combination of these elements to have a slide.  If the weather and snowpack are unstable, but you are on flat terrain, you won’t have an avalanche.  Or, if you are in avalanche terrain, but the weather and snowpack are stable, you probably won’t have an avalanche. 

Thinking in terms of this triad also makes it easier to extrapolate decisions when you are unsure of one of the factors.  If you are in a) avalanche terrain and know it has been b) storming for the last two days, it’s a safe bet that you will trigger some slides, even if you know nothing about c) the stability of the snowpack.

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Inside Info – Part I

Published on July 30, 2008 in 07 Avalanche Avoidance. 0 Comments Tags: , , .

(continued from Monday’s ABC’s of avalanche train of thought)

With so many variables hidden under a blanket of white, where do you even begin?  Simplify the process by breaking it down into the big three categories; terrain, snowpack and weather.

Will it stay, or will it go now? New snow, steep slope and a clear day... what to do?
Will it stay, or will it go now? New snow, steep slope and nice weather…

Terrain is the easiest.  If golf courses are too flat to avalanche and vertical walls won’t hold snow, the prime avalanche angle must be somewhere right in between.  As it happens, 38 degrees is the magic/tragic angle where avalanches are most likely to occur.  For reference, this is about as steep as an expert slope at a ski resort, or in other words, perfect ski mountaineering terrain.

Weather is the next factor and has a direct correlation with avalanches.  Stable weather means stable snow, and turbulent weather means turbulent snow.  The important weather information is its history, not necessarily what it is doing at the moment.  Statistically, most avalanche accidents happen just after a storm when the weather has cleared, but the snowpack is still adjusting to its new loading.  New snow is the big, obvious ogre, but wind is the evil villain that lays hidden deadly traps.  Rapid warming creates unusual avalanches and rain would be far more dangerous if it wasn’t so unpleasant to ski in.

continued tomorrow…
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Snap, Crackle & Pop – The ABC’s of Avalanches

Published on July 28, 2008 in 07 Avalanche Avoidance. 5 Comments Tags: , .

The physics of an avalanche is as easy to understand as placing one book on top of another, then tipping the lower book up until the top one slides off.  Voila – a bookalanche!  The grip or amount of friction between the books will determine how easily they slide apart.  If they are both dry and glossy, they’ll slide apart at almost any angle, but, if they have somehow bonded together through heat, humidity or moisture, you can turn them upside down and they may not come apart. 

 

One of my all time favorite avalanche education tools was this demonstration by the Alaska Avalanche School where layers of flour and sand are piled up on a flat board, which is then tipped up to 38 degrees where it rips loose and crushes the toys below.
One of my all time favorite avalanche education tools was this demonstration at the Alaska Avalanche School where layers of flour and sand are piled up on a flat board, which is then tipped up to 38 degrees where it rips loose and crushes the toys below.

This book example illustrates two important concepts of avalanches.  One, avalanches occur when a bond (friction) fails, and two; it can be difficult, if not impossible to predict exactly when that bond will fail without some additional information.  At times you could turn a mountain range over and shake it without the snow moving and at other times it will avalanche if you gently poke it with a ski pole.

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Avalanche Avoidance – Salvation Through Education

Published on July 22, 2008 in 07 Avalanche Avoidance. 4 Comments Tags: , .
It would be ideal of avalanche education was like driver’s education, where you studied and learned about the activity before physically doing it.  But alas it is not, and some skiers go their entire lives without taking a class.  Bad idea!  A lack of avalanche education should not be considered a backcountry badge of honor.  To make matters worse, the longer a skier goes without taking a class, the less likely they are to do so.  Someone who has been skiing for fifteen years is not going to be seen dead in an Avalanche Level 1 course.
Pitting out. Like a college degree, the actual information you learn in an avalanche class is secondary to learning the terms and methodology.
Pitting out. Like a college degree, the actual information you learn in an avalanche class is secondary to learning the terms and methodology.

Avalanche education has a constantly changing curriculum that is worth keeping up on.  It is important to get in the habit of continuing education with avalanches, and the pros do it all the time through seminars, meetings and trade journals. 

More than anything, classes force you to think about avalanches, practice safe skiing, familiarize yourself with your beacon and look critically at snow.  Plus, they are often good places to meet partners with similar levels of enthusiasm and skills.

Avalanche education also helps to develop your vocabulary, which in turn is useful for deciphering avalanche forecast reports.  Learning that a “westerly front produced significant cross-loading on mid elevation ridgelines” doesn’t help you much if you have no idea what they are talking about!

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